This week alone, already two terror threats linked to the Islamic State group have come through the encrypted messaging app Telegram. But the app, which the extremist organization has infamously been using since last year to communicate and spread propaganda, isn't the only tech tool in ISIS's digital arsenal.

"Just as smart phones and portable devices have transformed the way much of the world communicates and interacts, jihadists, too, have rapidly adopted and availed themselves of these technologies," cybersecurity company Flashpoint wrote in a study released last month. "These technologies are imperative to jihadist operations ― whether for escaping surveillance, maintaining presences in underground channels, or obscuring tracks to war zones. Jihadist groups undeniably owe countless aspects of their perpetuated existence to the internet."

Here are seven of the apps Flashpoint and digital media outlets have uncovered ISIS using:

Twitter. ISIS is known for using the social media site Twitter to recruit people. The Brookings Institution has estimated that ISIS supporters run up to 90,000 Twitter accounts. ISIS women, in particular, have formed a Twitter community to reach out to potential converts, BuzzFeed reported last year.

WhatsApp. Although at one point ISIS warned its followers to avoid this cross-platform messaging app, the group has used WhatsApp in the past to sell sex slaves, according to the Associated Press. Suspects also partially planned the November 2015 Paris attacks on the app, which introduced end-to-end encryption this past April, CNN reported.

Alphabet. ISIS launched this Android app earlier this year to teach children Arabic letters. The app has cards that show phrases — like "Za is for zakhira" — paired with illustrations — in this case, ammunition, Vocativ reported.

Amaq News Agency. This Android app shares articles from the ISIS-affiliated media outlet and has been updated multiple times, according to Flashpoint. In June, though, ISIS started to worry about a fake version of the Android app it thought was being used to spy on them.

Skype. This video chat program has been used by ISIS to recruit Americans and talk with reporters. In "ISIS: Inside the Army of Terror," Michael Weiss and Hassan Haasan wrote that when they Skyped with an ISIS source, they knew "each time we switch off could be the last we ever hear from him."

Al Bayan Radio. This app, which came out earlier this year, lets people listen to Al Bayan, an ISIS radio station. One ISIS follower called it "an amazing project" for allowing people to tune in "at every moment," Vocativ reported.

Alrawi. Reports began circulating in mid-January that ISIS had developed its own Android app, called Alrawi.apk, to disseminate news and communicate. By the end of the month, the Daily Dot had debunked the rumor, saying it was unable to find any evidence of a communications-enabled Alrawi.